Measurement of postural sway is used to investigate the effects of drugs, toxins, and aging on the neuromuscular system and to devise strategies to help elderly individuals reduce the risk of falling. One popular method of measuring sway is to use a force platform to monitor the path of the center-of-pressure. Currently, force platforms are expensive and most are designed for more demanding applications than monitoring sway. Under a highly successful Phase I SBIR grant, new technology was integrated in a prototype stability platform. Phase-I showed great promise for simplifying sway-measurement hardware and significantly reducing the cost of stability of stability platform systems. Under Phase II, it is proposed to refine the design of the stability platform, build five prototypes, and submit them to five practitioners for field tests. In the field, the stability platforms will be tested in parallel with existing force platforms. The tests will encompass a variety of applications and protocols. The results from the tests and the experience in the field will be reported to AMTI for analysis and for comparison of the types of platforms. Finally, the recommendations from the Phase II effort will be applied in a design for Phase III commercialization.